Rolling bodies (e.g. roller gear tables) and their corresponding guides on which they run are used for the low-friction performance of movement sequences, particularly linear movement sequences, for which a specific linear or longitudinal guide system type has been designed. Numerous longitudinal guide systems with rolls, balls and other rolling bodies are known. What is always sought is a very low-friction relative movement between two bodies, e.g. a guide or path and an element movable thereon, i.e. the rolling body. Nowadays such longitudinal guides are a function of the components of conventional ball bearings, whereof numerous different constructions exist. It is common to all of them that the balls are arranged in a row, which are collected in lined up manner in a ball race or cage. An example is provided by U.S. Pat. No. 2,952,145, in which two rows of balls are so arranged with respect to one another that they roll on one another. The object is to minimize sliding friction, but this only occurs in the indicated construction if the force pattern through the loading passes precisely through two ball pairs. However, this loading case is critical and cannot be maintained in operation, because the two parts displaceable relative to one another and mounted on balls undergo reciprocal turning and even the slightest rotation means that the apparatus is not operating in an optimum manner. Thus, there is no real operating case leading to the objective of the aforementioned U.S. Patent because, as stated, this construction cannot absorb a "sloping" force application without a considerable rise in the sliding friction. Thus, despite the symmetry of the solution the optimum force application is limited to a single point for each pair of balls.
Due to the necessary manufacturing precision, these rolling bodies with the always associated race-way are generally expensive and for most applications specially adapted types or constructions have to be used. However, this means that they can only be used in one field and there is no universal usage.
Roll guidance systems exist which comprise a guide rail and two associated guide blocks, which are interconnected by means of a web to form a guide carriage (rolling body). When the guide block moves on the rails, the balls revolve in closed ball races via a return channel. Such ball rotation elements are particularly suitable for large distances and can be operated in any position. However, such ball rotation paths are also subject to problems and in the case of rolling element return guides, feed impacts of said elements must be avoided, which involves corresponding technical expenditure. For example, the balls must be pressed with a constant pressure against the guide contact surfaces of the rail. This is also necessary in order to bring about a stick-slip-free displaceability. In addition, it is generally necessary to use profile-ground raceways. Although these solutions are robust and proven, they are complicated and expensive.
For the lowest possible friction, guide rails exist with single-row flat ball cages and the rolling elements are in two-point contact with the raceways. These linear guides adapt in optimum manner to the loading direction and are not sensitive to angle errors in the transverse direction. They are not suitable for passing round curves. Preference is given to the use of needle rolls, cylinder rolls, etc. with which loose bearings are also possible in flat cage guides.
In general, ball rails for ball guides are used for higher speeds and loadings. Roll rails are suitable for exact adjusting movements. Ball guides are robust and roll guides, particularly cross roll guides, are precise (clearance-free).